Passenger seats of automobiles or trains, various kinds of sofas, office chairs, and the like are often formed by attaching a skin material such as fiber fabric or natural or synthetic leather to the surface of a cushion body (foaming body) molded in a predetermined shape by using a foam resin material. The cushion body used in these various seats often has a curved surface composed of convex-concave shapes satisfying human engineering factors in order to maintain a seating posture which provides no fatigue despite long-hour seating.
Moreover, when a skin material is attached to the surface of a cushion body, after molding the cushion body in a desired shape, a method of covering and fixing a skin material to the surface of the obtained cushion body is often employed. In particular, in this case, a molded surface fastener is generally used as means for fixing the surface of the cushion body and a rear surface of the skin material.
A molded surface fastener has a configuration in which a plurality of engaging elements (male engaging elements, for example) are disposed on one surface (first surface) of a base portion made from a thermoplastic resin, and such a molded surface fastener is integrally molded so that the engaging elements are exposed to the surface of the cushion body when the cushion body is molded. Moreover, a plurality of female engaging elements configured to be fastened to the engaging elements of the molded surface fastener are formed on the rear surface of the skin material that covers the cushion body.
After the skin material covers the cushion body to which the molded surface fastener is integrated, the female engaging elements (loop-shaped engaging elements) disposed on the rear surface of the skin material are pressed against the male engaging elements of the molded surface fastener disposed on the surface of the cushion body, whereby the skin material is fastened to the molded surface fastener. In this manner, the skin material is easily fixed to the surface of the cushion body along the convex-concave shapes of the surface, and the skin material is prevented from floating from the cushion body.
Examples of such a surface fastener integrated to the cushion body for fixing the skin material are disclosed in WO 2012/025980 (Patent Document 1) and WO 2013/061423 (Patent Document 2).
In such a surface fastener described in Patent Documents 1 and 2, a plurality of hook-shaped engaging elements stand on a flat plate-shaped substrate portion to form an engaging region which enables engagement with loop-shaped engaging elements.
When the surface fastener of Patent Documents 1 and 2 are integrated to the cushion body, a groove portion for fixing is provided on a surface portion of the cushion body to insert and fix a part of the skin material, and the surface fastener is integrated in a state that the substrate portion of the molded surface fastener is disposed in a groove bottom portion of the groove portion for fixing in substantially parallel to the surface of the cushion body, and the engaging region faces a side of an opening of the groove. Thereby, the engaging region of the molded surface fastener can be exposed largely inside the groove portion of the cushion body in a groove length direction and a groove width direction, which enables stable engagement of the female engaging elements of the skin material.
Meanwhile, since the substrate portion of the molded surface fastener in Patent Documents 1 or 2 is disposed in the groove portion for fixing a skin material of the cushion body in substantially parallel to the surface of the cushion body, the groove width of the groove portion for fixing the skin material provided on the surface portion of the cushion body needs to be large to a certain degree, and the engaging region of the molded surface fastener needs to be exposed sufficiently in order to obtain an appropriate engaging force to engage the skin material.
However, a large groove width of the groove portion provided on the surface of the cushion body may cause a looseness of the skin material attached to the cushion body. Further, the engaging portion of the skin material for engaging with the molded surface fastener of the cushion body may appear to recess in a strip-shape, which lowers quality of an outside appearance of a product depending on the product to which the cushion body is used.
In order to solve such a problem, Utility Model Publication JP63-85200A (Patent Document 3) discloses a method placing a molded surface fastener in which an engaging region is formed by hook-shaped engaging elements along a side wall portion of a groove portion for fixing a skin material provided on a surface of the cushion body.
As the surface fastener is provided on one side wall portion of the groove portion in the cushion body so that the substrate portion of the surface fastener is disposed in a direction perpendicular to the surface of the cushion body, and the engaging region of the surface fastener is exposed in the groove portion, an appropriate engaging force can be secured by narrowing a groove width of the groove portion for fixing the skin material provided on the surface of the cushion body, and exposing an engaging area of the engaging region of the molded surface fastener sufficiently.
Therefore, the skin material can be stably engaged with the surface fastener of the cushion body, which can prevent looseness of the skin material attached to the cushion body, and an outside appearance of a product to which a cushion body is used can be improved.
U.S. Pat. No. 5,101,539 (Patent Document 4) discloses a cushion body in which a surface fastener is integrated to a groove portion for fixing a skin material provided on a surface portion in a curved shape so as to have a cross-section in a substantially U-shape, and engaging elements of the surface fastener are placed on both side wall portions facing each other in the groove portion for fixing a skin material.
Since the surface fastener is provided in the groove portion for fixing the skin material of the cushion body as mentioned in Patent Document 4, a large engaging area of the engaging region of the surface fastener can be secured, and a groove width of the groove portion for fixing the skin material provided on the surface portion of the cushion body can be narrowed, as in Patent Document 3.
Further, in Patent Document 4, one of embodiments is that the surface fastener integrated to the cushion body has a plurality of hook-shaped engaging elements, and a hook portion disposed at a tip end portion of each engaging element extends only in a direction toward a groove bottom portion of the groove portion of the cushion body (see FIG. 4 of Patent Document 4).
As the hook portion at a tip end portion of each engaging element in the surface fastener extends only in a direction toward the groove bottom portion of the groove portion, a part of the skin material can be easily inserted into the groove portion of the cushion body. Further, even if a part of the skin material is pulled to be removed from the groove portion of the cushion body after the hook-shaped engaging elements of the surface fastener disposed in the groove portion of the cushion body are engaged with loop-shaped engaging elements disposed on a part of the skin material, the engaging state can be stably maintained, and it can be prevented that the skin material is separated from the cushion body.